PROJECT ABSTRACT In the past six months, over 2,000 cases of vaping-related lung injury have been identified in 49 states, with 39 deaths. These injuries are taking a disproportionate toll on young people: the median age of these cases is 24 years and 54% of patients are youth or young adults under the age of 25. While evidence indicates that vaping THC plays a major role in this outbreak, the epidemic coincides with rapid increases in e-cigarette use in youth over the past two years. Time-sensitive information from young people on perceptions, patterns, and problems associated with vaping THC and nicotine is needed to guide state-level efforts. In the fall of 2019, the Vermont Department of Health launched the emergency Health Operations Center to track and respond to the state?s vaping-related lung injuries. As one of its early actions, the Center solicited data on vaping from the Policy and Communication Evaluation Study (PACE Vermont; www.pacevt.org), a six-month pilot study with quarterly online surveys in 1,500 youth and young adults completed in October 2019. The PACE Vermont Study is a partnership between the University of Vermont and the Vermont Department of Health to understand the impact of state-level policies and communication campaigns on substance use beliefs and behaviors in young Vermonters. This proposal continues the approach developed in the PACE Vermont Study to rapidly inform the VT HOC?s response to the outbreak of vaping-related lung injury. Expedited review and funding will allow for three additional waves of data collection in 1,500 Vermont youth and young adults to address questions raised by the VT HOC and the study team that would otherwise be impossible to obtain. Study aims address three areas: 1) changes in perceptions, patterns, and symptoms associated with vaping nicotine and marijuana in Vermont youth and young adults following the emergent outbreak of vaping-related lung injury; 2) characteristics of those who vape nicotine and marijuana, as well as those who report vaping-related symptoms or problems to guide intervention efforts; and 3) the impact of e-cigarette prevention messages on vaping-related harm perceptions and patterns of use. This proposal harnesses an experienced research team with expertise in rapid and responsive research, an established structure, and a community-engaged approach to address the rapid increase in vaping among young people and the emergence of vaping-related injuries. Partnership with the Vermont Department of Health and ongoing coordination with its emergency Health Operations Center ensures that data collected in this study will be rapidly incorporated into responses to these sudden and severe emerging drug issues in Vermont and potentially other states.